Laser scanning microscopy is widely used in semiconductor fabrication. For example laser scanning microscopy may be used to perform soft defect localization, in which soft defects, such as timing marginalities, are detected in fabricated semiconductor devices. Soft defect localization typically utilizes a laser to scan regions of a semiconductor device under test. As the dimensions of modern semiconductor devices become ever smaller, the resolution required to isolate individual device features for soft defect analysis grows correspondingly higher.
High resolution imaging of semiconductor devices can be achieved through use of a dark field microscopy approach employing a solid immersion lens (SIL). In order for such an approach to achieve the imaging resolution required by the smallest device dimensions, the imaging light incident on the target should be supercritical light, capable of producing evanescent fields within the semiconductor material housing the target. In addition, it may be necessary to collect the light scattered from the target along or near the central axis of the SIL. Consequently, a laser scanning module capable of creating supercritical light using an optical isolator to scan a target while concurrently enabling collection of light scattered by such a target is a desirable feature for use in laser scanning microscopy.